Oil burner control



Jan. 1, 1935. H. R. CRAGQ 9 1,985,978

OIL BURNER C ONTROL Filed Feb. 24, 1950 l-ILS Attor-nerg Patented Jam l, 1935 UNITED STATES OIL BURNER CONTROL .Harry B. Crago, Schenectady. N. Y., assigner to General Electric Company, a corporation of New Yori:

Application February 24, 1930, Serial No. 430,400

My invention relates to burner control devices, and has for its principal object an improved voltage failure protective arrangement in a fully automatic control device for a fuel burner. v

The present invention may be usedwth advantage in an automatic oil burner control de vice such as set forth in a copending application of Chester I. Hall, Serial No.H-i30,497,v filed Feb. 24, 1930 and assigned to the same assignee, al though not necessarily limited thereto.

Briey. the object of my invention is to prevent the occurrence of dangerous conditions in the re box in the case of voltage failure by preventing the energization of the apparatus supplying fuel to the furnace until the furnace has cooled to a safe temperature.

The usual fluid fuel burner employs an electrically driven fuel supply motor for furnishing f fuel to the combustion chamber of the oil burner furnace. necessary and this is usually an electricalignition system. A control mechanism is usually provided for controlling operation of the fuel supply motor and ignition systems. A room thermostat responsive to room temperatures in turn controls operation of the control mechanism to start and stop the burner in response to temperature variais described in the Haii'application, in the con trol mechanism a motor is provided for driving what is termed a recyciing mechanism having cam operated switches for opening and closing the ignition and fuel supplymotor circuits at short intervals, thus presenting several, oppormin nities for igniting the oil spray. When the is established a name responsive device placed in the rire box or Stacie of a furnace and operated by the flame cuts out the ignition 'system and locks in the fuel supply motor. The interv/'els of oper= ation are so spaced that any gases in the lire boi; are permitted to be drawn off by natural draft during the period when the motor and ignition system are deenergized.

in accordance with my present invention' a voltage failure responsive deviceis arranged to cooperate with the 'ierne responsive device the recycling mechanism" in such e, wey es to prevent lafter a voltage failure startin of the foei suppiy motor until the recoins-ive i has returned to i Some means for igniting the fuel is` 'contact o2 respectively. 'set to maintain diiferent temperatures and one dangerous accumulation of oil in the lire box can result from operation of the fuel supply motor.

My invention will be better understood from the following description when considered in connection with the accompanying drawing, and its scope will -be pointedout in the appended claims. y

In the drawing, the single figure is a schematic diagram of my invention.

Referring to the figure, the fuel supply motor 76 is provided with an ignition device including the spark producing terminals '78 connected to the secondary of the ignition transformer 77 by means of conductors 105 and 106. A flame responsive mechanism 85 whose function will be described later is mounted in the combustion chamber of the oil burner furnace, not shown. Mounted on the oil burner furnace is the safety switch mechanism 84 which may be a pressure operated or thermostatically operated mechanism responsive to either excessively high pressures or excessively high temperatures at the furnace;

The control mechanism for the oil burner fuel supply motor and the ignition system includes a synchronous motor 60 continuously energized from the power supply lines L3 and L4 by means of conductorsll and 111. This motor drives a gear transmission 60' of a time switch designoted generally by the numeral 61. The contact members o2 and e3 of the time switchare con necteci to thermostat biades 33 and 32 by means of conductors 92 and 92. The function of this cloclr. mechanism is to place either thermostat S2 or thermostat in the contini circuit controlling operati of the oil burner appare-tus when the switch 61 is on contact 63 or on These` therinostats are.

may he placed in the circuit during the night for maintaining one temperature and the other piaceri in the circuit during the day to maintain the other temperature. This clock control mechanism does not form a part of this application hot is described and claimed in a copending application of R. Townsend, Serial No. 399,835, filed Get. 15, i92ii, and assigned to the same assignee es the present application.

The motor e@ also furnishes the motive power for actuating the c ci mechanism which ceni. v .i

t c fuel F rer and igr'tion reu-its.

motor or the ignition system cannot be completed until contacts 73 and 73' are closed in a manner to be described below. These spring mounted switches are actuated by means of Ycams 67 and 68 under certain conditions. These cams are mounted on a cam shaft 66 which is rotatably supported by pivoted member 69 pivotally mounted in the `support 69. Cam 67 has aplurality of depressions and raised portions at 671 to produce intermittentenergization of the fuel supply motor as will be described. Cam 68 has only one depression 681 to open the ignition circuit under certain conditions. Mounted on shaft 66 is also a driving gear 65 which, when engaged by the pinion 64, rotates the camshaft in a counterclockwise direction. Cam 65 has a sector removed at 65 for a purpose to be described. The member 69 and cams are shown in an inoperative position to which they are normally biased. The member 69 is maintained in the position shown against further movement by means of the stop member 691. The springs 68 and 67' xed to a supporting panel not shown and cooperating with cams 68 and 67 are for the purpose of returning the camshaft to the initial' position shown whenever the cams are returned to inoperative position from engagementwith switches 74 and 75 as will be described. The springs 68 and 67 are placed under tension when the cam shaft is rotated in a counter-clockwise direction. When the cams are brought out of operating en,- gagement with switches'74 and '75, this' stored up tension causes the springs to rotate the cams in a clockwise direction to their initial position.

The means for establishing the driving connection between the gears 64 and 65 is the electroresponsive device 70 which, when energized, exerts a pull on the member 69 to rotate it in a clockwise direction to place gears 64 and65 in driving relation and to move the cams 67 and 68 into operating engagement with the spring actuated switches 75 and 74. Upon movement of the cams into operating engagement, cam 67 opens the switch 75 and cam 68 closes the switch 74. 'Ihe circuit through the motor is thereby opened and the circuit through the ignition system is thereby closed if the contacts 73 and 73' are closed. I

A second armature 72 pivoted at 72 and biased to open position is associated with a second electro-responsive means 71 which exerts only a sulcient pull on armature 72 .to maintain it in the closed position after vit has once been closed. The member 69, when rotated in a `clockwise direction, contacts with the armature-.72 to rotate it in a counter-clockwise direction to close contacts 73 and .73' to close the ignition and fuel supply motor circuits to one side of the line La as will be described below. j

The transformer 81` which is connected to the supply lines L3 and L4 by means of conductors 115 and 116, furnishes a low voltage supply for the control mechanism, as will be described. The transformer 80 is a locking transformer and its function will be described below.

The operation is as follows: Assuming the switch arm 61 to be in engagement with contact 62, the thermostat 83 will be placed in the control circuit. When heat is called for by movement of the thermostat 83 to the left-hand contact, a circuit is completed from the lower side` of the secondary of transfor er 8l through conductors 90 and 91, left-hanl contact of thermostat 83, conductor 92, contact 62, switch member 61', conductor 79, safety switch 84, conductor 93,

electro-responsive device 71,`conductor 94, electro-responsive device 70, conductors 95 and 96, back to the upper side of the secondary of transformer 81.

This causes energization of the electro-responsive devices 71and 70. Electro-responsive device exerts a pull on the pivoted member 69 to rotate it in a clockwise direction placing gears 64 and 65.in driving relation to rotate the camshaft 66 in a counter-clockwise direction. The cams 67 and 68 are brought into engagement with the spring switches .and 74, opening switch 75 and closing switch 74. As the pivoted member 69` is rotated 4in a clockwise direction, it contacts with the armature 72 to rotate it in a counter-clockwise direction to close contacts 73 and 73.

'Ihis results in energizing the ignition'system. The circuit through the primary of the ignition transformer 77 can be traced as follows: From the supply line L4, conductor 103, to one side of the primary of the transformer, from the other side of the primary of the transformer, through conductor 102, closed switch 74, conductor 104, conductor 104', closed contacts 73 and 73, armature 72, conductor 101, to the other side of the line La. This, of course, energizes the secondary of the transformer which is connected ,to the terminals 78 by means of conductors 105 and 106 and causes a spark'between the terminals.`

At the same time, the locking transformer 80 which is normally unenergized is energized when the contacts 73 and 73 are closed. One side of the primary ofthe transformer is energized' of Ithe transformer 80, through conductor 112, v

conductor 96, conductor 95, electro-responsive device 70, conductor 94, electro-responsive device 71, conductor 93, safety switch 84, conductor r19, to the other side of the secondary of transformer 80. It will thus be seen that since the electroresponsive devices 70 and 71 are energized from the secondary of transformer 80, and since they maintain the primary of the transformer energized, the transformer is electrically locked across the supply lines.

As the camshaft is rotated counter-clockwise the first depression at 671 in cam 67 is reached permitting the spring switch 75 to move to the closed position. This energizes the fuel supply motor 76. The circuit therethrough may be traced as follows: Supply line L4, conductor 97, fuel supply motor 476, conductor 98, switch 75, conductor 99, conductor 100, conductor 104', contacts 73 and 73 in the closed position, armature 72, conductor 101, back to the other side of the line La.

,This supplies fuel to the combustion chamber of the oil burner furnace which is usually ignited by the spark between the terminals 78. `If com? bustion is established, the combustion responsive device responds to close the bridging member 107 on the contacts 108 and 109. This shunts out the electro-responsive device 70 deenergizing the same and permitting the pivoted member 69 to return to the inoperative position, disengaging the gears 64 and 65 and permitting the switch 74 to open to break the circuit through the ignition transformer when the cams move out of engagement with the switches. As described above, springs 68' land 67 then return the cams to initial position. Since the electroresponsive device 71 remains energized, the armature 72 will remain in its operative position with the contacts 73 and 73 energized. Since the switch 75 is in the closed position, the fuel supply motor 76 will also remain energized to supply fuel to the combustion chamber of the oil burner furnace.

If combustion is not established when the switch member 75 falls into the first depression on cam 67 as the cams rotate, the switch 75 is opened by the first raised portion of the cam surface to open the motor circuit. It is maintained open a sufliciently long time to permit the oil spray to be drawn from the combustion space of the oil burner furnace by natural draft before switch 75 drops into the next depression on cam 67 to again close the motor circuit.

After several repetitions of energization and deenergization of the fuel supply motor, the gear 65 will have rotated to such a position that the broken-away segmental portion 65 will reach the pinion 64. At this time the switch member 75 is on the raised portion of cam 67 following the portion 671, thus deenergizing the fuel supply motor circuit, and the switch' 74 isl in the depression 681 on cam 68 permitting it to open thus deenergizing the ignition circuit. Since gear 64 can no longer drive gear 65, no further rotation of the camshaft can be obtained and the cams and switches remain in this position until a personal inspection is made to determine the cause of improper operation of the oil burner apparatus.

If the thermostat 83 calls for a shut-down of the apparatus by moving to the right hand contact, the secondary of the transformer 80 is shorted, therebyopening up the circuit through the electroresponsive device 71 which releases its armature 72 to open the contacts 73 and 73 and thus the circuit through the motor 76. The shunt circuit may be traced as follows: From one side of the secondary of transformer 86, conductor 112, conductor 113, right-hand contact of thermostat 83, conductor 92, contact 62, switch 61', conductor 79, to the other side of the transformer 80. Upon cooling down of the furnace, the flame responsive device 85 again returns to its open position so that the electroresponsive device 70 is again placed in the circuit.

The cams of the control device are so set that during the intermittent operation a sufficient time elapses between each operation of the fuel supply motor to permit any accumulated gases in the fire box to be dissipated by a natural draft.

l Should the operation of the oil burner be interrupted by a temporary voltage failure the recycling device will not operate to reenergize the ignition system and fuel supply motor until the fire box has sufficiently cooled to permit the flame responsive device 85 to open its contacts.l This prevents ignition with the rebox full of oil vapor which would cause an explosion. Until the contacts of the flame responsive device 85 are opened, the electroresponsive device 70 can not be energized, thus preventing closing of the fuel supply motor and ignition circuits. When the contacts open upon cooling, the recycling apparatus is set into operation to operate the motor and ignition circuits. This lapse of time permits the dissipation of accumulated oil vapors and prevents oil being pumped into a hot re box.

It will thus be seen that I have provided a fully automatic device which is safe in operation for the control of an oil burner furnace.

The embodiment of the invention illustrated and described herein has been selected for the purpose of clearly setting forth the purpose involvesl. It will be apparent however that the invention is susceptible of being modified to meet the different conditions encountered in its use and I therefore aim to cover by the appended claims all modifications within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In an oil burner control, in combination, a

fuel projecting motor, an ignition system therefor, cam operated switch mechanism for initiating combustion by energizing the ignition system and by intermittently energizing said fuel supply motor to produce a flame, means for driving said cam operated switch mechanism, electro-responsive means adapted to maintain said fuel projecting motor energized until a temporary failure of voltage occurs, temperature responsive means for controlling said mechanism to cause operation thereof by its driving means, and for deenergizing said second means when more than a sufficient amount of heat is supplied to maintain a desired temperature, a combustion responsive device initially in a cold position to permit actuation of said switch mechanism and movable to a hot position on establishing combustion to maintain said second means energized and render said switch mechanism inoperative and maintaining said switch mechanism inoperative after a failure of voltage until said combustion responsive device returns to the cold position when initial conditions are obtained.

2. In an oil burner control, in combination, an electrical driving motor, a fuel supply motor, an ignition system therefor, switches controlling energization of said fuel supply motor and ignition system, a cam mechanism cooperating with said switches and adapted to be driven by said driving motor, said cam mechanism operating said switches for controlling energization of said ignition system and intermittent operation of said fuel supply motor by said switches to initiate combustion, an electroresponsive device provided with an armature for establishing driving connections between said electrical driving motor and said cam mechanism, a second electrore` sponsive device, provided with an armature and operatable only to hold the same after it has been moved for maintaining said fuel supply motor energized to maintain combustion after it has been established until a temporary failure of voltage occurs, the armature of the second electro-responsive device being actuated by the actuation of the armature of the first electro-responsive device to attracted position to maintain said fuel supply motor energized when said rst electroresponmeans, electroresponsive means for controlling,y

operation of said cam mechanism by said driving motor to initiate combustion, a circuit controlling member movable between open and closed position for maintaining said fuel supply motor energized after combustion is established to I'maintain combustion, electroresponsive means for maintaining said last circuit controlling member in a closed position until a temporary voltage failure occurs, means responsive to combustion for rendering said first electroresponsive means inoperative until initial conditions are obtained after a voltage failure, and temperature responsive means for energizing said first electroresponsive means to initiate heating conditions and to deenergize said second electroresponsive means to deenergize said fuel projecting motor when more than sucient heat is furnished -to maintain a predetermined temperature.

4. In an oil burner control, a fuel supply motor, circuit making and breaking means for controlling said fuel supply motor to initiate combustion, an electroresponsive means, a movable member actuated bysaid electroresponsive means, said movable member supporting cams for operating said circuit making and breaking means, a driving means for said cams, a voltage responsive circuit making and breaking member for maintaining said motor energized to maintain combustion after combustion is establishedL and means on said movable member to actuate said voltage responsive circuit making and breaking member to energizing position upon energization of Isaid electroresponsive means, and means responsive to combustion for rendering said electroresponsive means inoperative until initial conditions are obtained after a voltage failure.

5. In an oil burner control, in combination, a fuel supply motor, a recycling means including a circuit making and breaking device for controlling said fuel supply motor to initiate combustion, a movable member carrying means for intermittently operating said circuit making and breaking device, a second circuit making and breaking device for controlling energization of said motor and an electroresponsive device for holding said second circuit making and breaking device in circuit making position to maintain said fuel supply motor energized after establishing combustion to maintain combustion, and means whereby when the movable member is actuated to establish operating conditions between said first circuit making and breaking device and the operating means on said movable member, said second circuit making and breaking device will be moved `to the circuit making position, and means responsive to combustion for rendering said recycling means inoperative until initial conditions are obtained after a voltage failure.

6. In an oil burner control, a fuel supply motor, a circuit making and breaking means for controlling said motor to initiate combustion, a cam shaft carrying circuitgmaking and breaking cams adapted to cooperate with said circuit making and breaking means, pivoted means supporting said cam shaft, a driving means, electroresponsive means for moving said pivoted means to cause said driving means to rotate said cam shaft, a circuit closing and opening member for controlling energization of said motorl and means on said pivoted cam supporting means to move said circuit closing and opening member to the closed position upon movement of said pivoted means to driving position and a second electroresponsive means for holding said pivoted member in a closed position to maintain said motor energized to maintain combustion, anda combustion responsive means operable upon the establishment of combustion to maintain energization of said second electroresponsive means and to deenergize said first electroresponsive means and maintain it deenergized until initial conditions are obtained after combustion failure.

7. In an oil burner control, in combination, a fuel supply motor, a circuit therefor, means for controlling said circuit, a camshaft carrying circuit-making and -breaking cams for cooperating with said circuit controlling means for controlling said circuit to establish combustion, meansadapted to drive said camshaft, a movable means supporting said camshaft, a movable circuit-opening and -closing member for controlling energization of said motor circuit, electroresponsive means for `moving said movable means to render said camshaft driving means operative, means on said movable means whereby movement of said movable means rendering the camshaft driving means operative4 will move the said member to circuitclosing position, and a second electro-responsive device for holding said member 'in circuit-controlling position to maintain said circuit energized under certain conditions, and means responsive to combustion for rendering and maintaining said rst electro-responsive means inoperative until initial conditions are again estab- .Y

lished after voltageI failure.

8. In control apparatus for a burner having an electrically operated fuel supplying means and an ignition system therefor, the combination of circuit controlling means for said fuel supplying means, electro-responsive means including a cam mechanism for operating said circuit controlling means intermittently to energize said fuel supplying means to initiate combustion, driving means for said cam mechanism, voltage responsive means for maintaining said fuel supplying means energized to maintain combustion after initiation thereof, and means for de-energizing said electro-responsive means in response to combustion and for rendering said electroresponsive means ineffective to re-establish combustion after a temporary failure of voltage until the combustion chamber temperature drops to a pre-determined value.

9.4 In combination, a burner having a fuel supplying means and an ignition system therefor, circuit making and breaking means adapted to control said fuel supplying means, electrically driven cam mechanism for intermittently operating said circuit making and breaking vmeans to initiate combustion, electro-responsive means for controlling operation of said circuit making and breaking means by said cam mechanism, a second electro-responsive device operatively associated with said circuit making and breaking mechanism for maintaining said fuel supplying means energized after combustion is established and a means responsive to combustion for deenergizing said first electro-responsive means and for rendering said first electro-responsive means ineffective to re-establish combustion after a temporary voltage failure until the combustion chamber temperature drops to a pre-determined level.

10. A heat control apparatus for a burner, n-

cludng a. plurality of electro-responsive means provided with individual armatures, one of said armatures being provided with means for caus ing intermittent operation of the burner to initiate combustion, thermostatic means for energizing one of said electro-responsive means to move said one amature to render said intermittent means effective, another of said electroresponsive means for maintaining the burner in operation when combustion is established and whose armature is moved to combustion maintaining position by actuation of the armature of said one electro-responsive means, and a combustion responsive means for rendering said one electro-responsive means inoperative after a temporary voltage failure until the combustion chamber temperature drops to a pre-determined level.

11. In a control for a burner having an electrically operated fuel supplying-means and an ignition system therefor, the combination of circuit controlling means for energizing said fuel supplying means, electrically driven cam mechanism adapted to operate said circuit controlling nieans intermittently to energize said fuel supplylng means to initiate combustion, electro-responsive means operatively associated with said circuit controlling means for rendering said cam mechanism operative, a second electro-responsive means rendered effective upon operation of said iirst electro-responsive means and o peratively associated withv said circuit controlling means for maintaining said fuel supplying means energized, means responsive to combustion conditions for de-energizing said rst electro-responsive means torender said cam mechanism ineifective and for preventing a re-energization of said rst electro-responsive means to render said second electroresponsive means effective after a temporary voltage failure until the combustion chamber temperature drops to a predetermined level.

12. Incombination, a burner having fuel supplying means and an ignition system therefor, circuitmaking and breaking means adapted to control said fuel supplying means, electrically driven cam mechanism for operating said circuit and breaking means intermittently to energize said fuel supplying means to initiate combustion, electro-responsive means for controlling operation of said circuit making and breaking means by said cam mechanism, a second electro-responsive means rendered effective upon operation of the first electro-responsive means and operatively associated with said circuit making and breaking means for maintaining said fuel Supplying means energized after combustion is established, temperature responsive means for controlling said first electro-responsive means to initiate combustion and for deenergizing said second electro-responsive means when more than a suflicient amount of heat is supplied to maintain a desired temperature, and means responsive to combustion and movable from a cold position to a hot position to deenergize said first electro-responsive means and to maintain said rst electro-responsive means ineffective to render said second electro-responsive means efective after a temporary voltage failure until the combustion chamber temperature drops to a level to permit said combustion responsive means to return to cold position.

13. In a heating apparatus, the combination of an electric motor driven fuel supply means, an ignition system, a thermostatic control device, means controlled by said device including an electric motor driven time switch mechanism for controlling said ignition system and for intermittently energizing said electric motor driven fuel supply means to initiate combustion, means responsive to combustion, voltage responsive circuit controlling means rendered effective jointly by said electric motor driven switch mechanism and said combustion responsive means to maintain said fuel feeding means continuously energized after combustion is established until a temporary voltage failure occurs and thereafter to maintain said fuel feeding means deenergized until initial conditions are obtained and connections whereby said thermostatic control device deenerglzes said voltage responsive circuit controlling means to stop operation of said fuel feeding means.

i HARRY R. CRAGO. 

